Meaning of “nuclear” - Learner’s Dictionary

nuclear

adjective [ always before noun ] uk us /ˈnjuːkliər/
ENERGY

B2 relating to the energy that is released when the nucleus (= central part) of an atom is divided:

nuclear weapons/waste
a nuclear power plant
PART OF ATOM

relating to the nucleus (= central part) of an atom:

nuclear physics

(Definition of “nuclear” from the Cambridge Learner’s Dictionary © Cambridge University Press)